But people are still not allowed to take in any liquids apart from baby milk and baby food, and prescription medicines.

BAA said anyone travelling over the next few days should allow extra time for their journey.

The airport operator has come under fire from several airlines who have been highly critical of the way it has managed its airports during the upheaval.

British Airways has said it may sue BAA, but Virgin Atlantic called on BAA, airlines and the government to sit down and discuss who should "pick up the cost" of the terror alert.

BA boss Willie Walsh has attacked BAA's management, saying it had "no adequate plan" to deal with the emergency.

He told the Daily Mirror that the resulting queues resembled a "bad dream at Disneyland".

Paul Charles, from Virgin Atlantic, talking about the situation at Heathrow and Gatwick, said: "The delays are less and the queues are less. It is clear some of the measures put in place are working.

"There is no doubt that the picture is better from a passenger perspective."

He said Virgin Atlantic was running a normal service, adding that it had been a frustrating few days "because we have been forced to cancel a handful of flights we would otherwise be running normally".

On Tuesday, a total of 45 flights were cancelled at Heathrow - one Jet Airways flight and 44 British Airways. Of BA flights, this includes four long-haul services, 21 short-haul and 16 domestic flights.

On Monday, the majority of flights got away on time, said a BAA spokeswoman.

We travelled home with a distressed baby and had to smash a window to get into our house

At Gatwick 11 flights have been cancelled - all on BA domestic routes - while at Stansted there have been eight cancellations of Ryanair flights.

Elsewhere, airports including Birmingham, Newcastle, Manchester, Edinburgh and Glasgow were reporting business was mostly back to normal after the less stringent measures were introduced on Monday.

The Times reports that transport officials are considering "passenger profiling", where airlines identify people who, on grounds of such things as conduct or appearance, they believe could pose a risk to security.

They are then subjected to more questioning or greater surveillance.

'Stereotypical terrorist'

Metropolitan Police Chief Superintendent Ali Dizaei said intelligence might be able to shed light on people's travel history, where they bought tickets, and the persistency of travel.

But he told BBC Two's Newsnight: "It becomes hugely problematic when it's based on ethnicity, religion and country of origin. I don't think there's a stereotypical image of a terrorist."

BAA's Tony Douglas said the airline industry had faced a "national security challenge" on an "unprecedented scale" in the past few days.

He said the situation was becoming more stable, with improved punctuality of flights at Heathrow and fewer cancellations.

But police at Gatwick have said there has been an increase in thefts from passenger baggage in transit during the recent security alert.

I'm glad to see security measures in place, and we can never be too careful with our lives